JPS5872377A - Controlling method for pwm control converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a P~'M control converter connected to an AC power supply system, and particularly relates to a control method for controlling active power and reactive power taken in by the converter from an AC power supply. .

Conventionally, it has been known to adjust the reactive power of an AC power system by controlling the phase of a thyristor connected in series to the current of a capacitor or reactor connected to the system.

However, these devices are expensive because they are provided separately from the load device, and there are problems in terms of installation space.

An object of the present invention is to provide a load device connected to an AC power supply with a reactive power function, so that the reactive power required by the grid can be optimally controlled, and the reactive power compensator as described above is not required. To provide a function conversion device.

The voltage-type pulse width modulation (hereinafter abbreviated as PWM) method can freely control the active power and reactive power taken in from the AC power supply by controlling the magnitude and phase of the AC input voltage. On the other hand, active power can be controlled by controlling the magnitude of the current component that is in phase with the voltage of the AC power supply, and reactive power can be controlled at 90 degrees with respect to the voltage of the AC power supply. This can be controlled by controlling the magnitude of the current component of the phase difference. therefore.

Detect a signal that is in phase with the AC power source and change its amplitude according to the active power, detect a signal that is 90 degrees in phase with the rechargeable AC power source, and change its amplitude according to the reactive power. The desired objective is achieved by controlling the AC input current of the converter in proportion to the sum of the signals.

FIG. 1 shows a circuit configuration diagram of a PWM control conversion device showing one embodiment of the present invention. 1 to 2 are P that converts alternating current to direct current
A WM control converter is constructed, and 1 is a converter consisting of a GTO and a diode, and 2 is a reactor. 3 is a smoothing capacitor for absorbing the ripples in the DC output current of the converter 1;
4 is a voltage command circuit that outputs a command signal of the DC input/output voltage of the converter 1; 5 is a voltage detector; 6 is a voltage deviation amplifier that matches and amplifies the voltage command signal and the voltage detection signal; 7 is an AC power supply A transformer for detecting system voltage, outputting signals with the same phase and signals with a 90 degree phase difference for each phase voltage. 8
is a current detector for detecting the current of an AC power supply system, 9
10 is a reactive power detector that detects the reactive power of the AC power supply system from the output signals of the transformer 7 and the current detector 8; 10 is a signal that is in phase with the AC power supply voltage from the transformer 7 and the output signal of the amplifier 6; 11 is a reactive power command circuit that generates a command value of reactive power of the AC power source; 12 is a command circuit 11 and a detector 9
a reactive power deviation amplifier for amplifying the deviation of the output signal of 13;
is a command pattern signal that multiplies the AC power supply voltage from the transformer 7 by a signal with a 90 degree phase difference and the output signal of the amplifier 12, and commands the reactive portion of the AC power supply current that the converter inputs and outputs.
Arithmetic circuit that generates reactive current command (hereinafter referred to as reactive current command), 14iJ:
A current detector 15 is used to detect the input current of the PWM converter 1, a comparator 15 has a hysteresis characteristic that compares the summed signal of the effective and reactive current pattern signals and the current detection signal, and 16 is a comparator 15. GTO according to the output signal of
This is a gate amplifier that outputs a gate signal to alternately turn on and turn off the P side and N side of Cyrisk. There are circuits corresponding to 14 to 16 for the other V-phase and W-phase, but since they are similar, their explanation will be omitted. In addition, 1
Reference numeral 7 denotes a waste load device that generates reactive power.

Next, the operation of this circuit will be explained. first.

A method for controlling active power will be described. A current control loop including the comparator 15 and the like can control the AC input/output current of the converter 1 according to the output signal of the arithmetic circuit 10.13. Since these operations are well known, detailed explanation will be omitted.

Since the current command signal output from the arithmetic circuit 10 gives a command for the effective current as described above, it is possible to control the component of the AC input current of the converter 1 that is in phase with the AC power supply voltage, that is, the active current. can. Since the effective current has a power balance between the AC and DC sides of the converter 1, the DC current can be controlled, and the DC voltage can be controlled by controlling the magnitude of the charging current of the capacitor. can do. The DC voltage ratio is detected by the detector 5 and compared with the command value, and the magnitude of the active power is controlled according to the deviation signal, so that the DC voltage is controlled to a predetermined value.

Next, a method for controlling reactive power will be described. Arithmetic circuit 13
According to the output of the converter, it is possible to control a current having a phase difference of 90 degrees with respect to the converter input voltage, as described above. That is, reactive power can be controlled.

When the magnitude of reactive power in the AC power supply system changes, the magnitude is taken in from the detector 9 and compared with the command value,
Since the magnitude of reactive power is controlled according to the deviation,
Reactive power is controlled to a predetermined value. Note that these active power and reactive power can be controlled completely independently, so
For example, even under conditions where the direct current is zero, reactive power can be freely controlled.

Therefore, according to the present invention, while supplying DC power of a predetermined voltage to the DC circuit of the converter, the reactive power of the AC power supply system can be controlled to a predetermined value.

In the embodiment shown in FIG. 1, reactive power is detected from the AC power supply side connecting the converter 1.2 and the load 17. However, the present invention is not limited to this, and reactive power is detected on the input side of the load 17. You may. In that case, the reactive power of the load 17 is controlled as follows. A reactive power detection signal detected from the input side of the load 17 is used as a command signal, and the arithmetic circuit 13 multiplies the signal and a signal having a phase difference of 90 degrees with respect to the power supply voltage.

Create a current pattern signal to cancel reactive power. According to the current pattern signal, an AC current having a phase difference of 180 degrees with respect to the reactive current of the load 17 flows through the AC input side of the converter 1, and is controlled so as to cancel the reactive power of the load 17. Therefore, according to this method, the converter can supply DC power of a predetermined voltage to the load of the DC circuit, and at the same time control the reactive power of the power source to be zero.

When the DC voltage system of the converter 1 is strong, the DC output current of the converter 1.2 is detected by the detector 20 as shown in FIG.
Even if the converter 1 is controlled in accordance with the deviation signal from the DC current command circuit 21, the active power of the AC power supply system or the DC output current can be controlled to a predetermined value. Also, in the embodiment shown in FIG.
A similar effect can be obtained by detecting the input active power.

According to the present invention, it is possible to supply DC power of a predetermined voltage to the negative f of the DC circuit using the converter, and at the same time control the reactive power of the AC power supply system to a predetermined value. Therefore, a reactive power compensator, which had to be provided separately, becomes unnecessary, and system costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a PWM control conversion device showing one embodiment of the present invention, and FIG. 2 is a PWM control conversion device showing another embodiment of the present invention.
It is a circuit diagram of a control device. 1...PWM control converter, 2...reactor, 3...
... Smoothing capacitor, 4... Voltage command circuit, 5...
Detector. 6... Voltage deviation amplifier, 7... Transformer, 8, 14.
...Current detector, 9...Reactive power detector, 10.13
... Arithmetic circuit, 11... Reactive power command circuit, 12.
...Reactive power deviation amplifier, 15...Comparator, 16...
- Gate amplifier, 17... Load device, 20... Current detector, 21... DC current command circuit.

Claims (1)

[Scope of Claims] L A converter that controls the magnitude and phase of AC input current and is connected to an AC power source, and a control circuit that controls active power and reactive power input and output by this converter. In the control of the converter, the converter amplitude-modulates a signal having the same phase as the AC power supply voltage according to the active power to be input/output from the AC power supply. The converter amplitude-modulates a signal with a phase difference of 90 degrees with respect to the AC power supply voltage according to the reactive power to be input/output from the AC power supply, and controls the two signals as a command pattern of the AC input current of the converter. P characterized by the fact that
Control method for WM control converter.